On the biggest night of the Indiana Pacers’ season, Frank Vogel has to go small and stay small.

Stop me if you’ve read this all before:

Sit Roy Hibbert.

Start a front line that features David West and Luis Scola at center and power forward.

And make Chris Copeland — the near-hero of Game5, helping Indiana slice a 27-point deficit to nine — a key part of the rotation.

“I saw some good things there (late in the third quarter and in the fourth quarter of Game 5),” Vogel said after Tuesday’s practice. “But I’m not going to talk a lot about adjustments or potential lineup changes we might make until game time.”

After five games and three victories by the No. 8-seeded Hawks, it’s abundantly clear Atlanta has dictated the terms of engagement to the top-seeded Pacers. Small has beaten big, occasionally embarrassed big. Speed has beaten lumbering. And energy has beaten whatever it is the Pacers are offering up in terms of effort, which isn’t nearly enough.

Game after game, Vogel has turned to the small lineup featuring West and Scola in the fourth quarter. So why not go with them in the first quarter? And second? And third, too? If that’s your winning-time lineup, if you feel you’re at your best when Hibbert is on the bench, what sense does it make to put Hibbert on the floor in the first place?

In theory, the Pacers should have bullied the Hawks, should have toyed with them the way the Miami Heat dispatched the Charlotte Bobcats. The Pacers won 16 more regular-season games than Atlanta, the only sub-.500 team in the postseason. They should have been able to play big, impose their size and physicality as they did last season against the Hawks, Knicks and Heat.

In theory.

Except it isn’t happening, and there’s no reason to think it’s suddenly going to happen in Game 6 and, maybe, a Game 7.

“Look, they’re a physical team; it’s not like they’re playing a point guard at the power forward spot,” Vogel said. “(Pero) Antic is a big, strong guy. Paul Millsap, (Elton) Brand, they’re big, strong guys. They have great physicality along with great 3-point shooting.”

The Pacers made their bones this season by playing inside-out, by playing through the post. But they’ve had limited success in that area in this series. The Pacers have been almost unrecognizable this series, their identity lost.

“Playing through David (West) has been efficient at times,” Vogel said. “Playing through Roy has been hit or miss.’’

Mostly miss.

The Hawks have this series exactly where they want it, playing their style, their pace, with their preferred personnel.

“It’s just different; they spread us out,” Paul George said. “We’re used to packing the paint, playing big and physical. It’s like playing pickup ball against them. There’s five perimeter guys on the floor. I don’t feel like they’re running any sets; they’re just playing the game, trying to see who has the advantage, who’s a step late (defensively). They’re swinging it, moving it, moving themselves, so it’s a different feeling playing these guys.”

Nobody is suggesting Copeland is the savior; effort, passion and desperation will be the the real game-changers if the Pacers are to push this series to a seventh game back home. But he gave Indiana a completely different look Monday, a good look, altering the spacing and geometry of the Pacers’ stunted offense. When he came on the floor, he played the role of Kyle Korver, standing beyond the 3-point arc, occupying a defender. That allowed teammates such as George and others to slash toward the basket and mount a comeback.

As the deficit dwindled from 27 points all the way down to nine, a light bulb should have gone on.

This works.

And it will work, if Vogel gives it a chance to work.

And talking to several Pacers the past two days, I sensed they want to give it more of a try, especially with Hibbert having the worst postseason ever by an All-Star participant.

“I definitely thought our spacing is better when we have shooters all over the court,’’ Copeland said in the locker room after Game 5. “And we have some of the best slashers in basketball in Paul (George) and Lance (Stephenson) and David (West) when he gets near the basket. When we have a lot of shooters, it gives them the opportunity to roam and to attack the basket. Even if I don’t shoot, I think I can still be a factor that way.’’

Said George: “I thought we did a great job taking advantage of it (the small lineup). The floor was so open, so spaced out. It was hard for them (the Hawks) to be in gaps and help. I liked that lineup we had on the floor.’’

To his credit, Copeland remained the ultimate good soldier Tuesday, acknowledging that while he’d love to get some minutes, he will accept whatever role Vogel finds for him. “It’s my job to stay ready,’’ he said.